Structural Design Past Paper - Engineering

# TARLAC STATE UNIVERSITY - College of Engineering & Technology ## Civil Engineering Department ### Engr. Orlando Cruz Sico Jr. ## CEP352/351C - Building System Design & Computation ## MODULE 4 # Structural Design - An art and science of understanding the behaviour of structural members (footi...

# TARLAC STATE UNIVERSITY - College of Engineering & Technology ## Civil Engineering Department ### Engr. Orlando Cruz Sico Jr. ## CEP352/351C - Building System Design & Computation ## MODULE 4 # Structural Design - An art and science of understanding the behaviour of structural members (footings, slabs, columns, beams, etc.) which are subjected to loads and designing them with economy to give a safe, serviceable and durable structure. ## Structural Plan - Designed by Structural Designer and used by engineers, especially Civil Engineers, concerning with the load-carrying members of the structure showing their details, specifications, and schedules. ### Objectives: 1. To determine the methodology to be used in constructing a project. 2. **Safety:** The structure should be able to carry all expected loads safely, without failure, that is, without breaking or collapsing under the loads. 3. **Stability:** The structure should not move (by sliding or overturning) under the expected loads. 4. **Serviceability:** The structure should not deform or crack unreasonably under the expected loads. 5. **Durability:** The structure should last for a reasonable period of time. ### Components of Structural Drawing 1. **Construction Notes & Specifications** - shows the general notes, methods, & specifications to be used during construction. 2. **Foundation Plan** - is a plan view drawing, showing the location and size of footings, columns, foundation walls, and supporting beams such as footing tie beam and grade beam. 3. **Framing Plan** - shows the location and sizes of columns, beams, and slab designations. 4. **Details** - separated plan showing the specific details such as cross section, steel reinforcement, sizes from a portion of a plan. 5. **Schedules** - schedule provides section, sizes, and steel reinforcement of beams, slab, column, and footing. ## Process of Structural Design ### A. Structural Planning & Layouting 1. **Ideal position & orientation of columns** - Columns should preferably be positioned symmetrically about the center of the building. - Should preferably be located "at" or "near" the corners of the building & at beam intersections. - Avoid larger center-to-center distance between columns. 2. **Established design criteria** - Selection of materials & their strength - Established all loads which the building requires. - Types of loads - **Dead Load** - includes the weights of all materials to be used in the building. - **Live Load** - building occupants including fixtures/furnitures - **Lateral Load** - wind & earthquake forces 3. **Structural Analysis** - Study of stresses, strains, & slope deflections of structural members. 4. **Structural Design** - Designing the members considering the strength, economy, & serviceability. 5. **Structural Detailing** - Preparation of structural drawings & informations needed for construction. ### Foundation Plan - is a plan view drawing, showing the location and size of footings, columns, foundation walls, and supporting beams such as footing tie beam and grade beam. ## MODULE 3. Structural Plans # Why a Foundation is provided - Distribute the weight of the structure over a large area of soil. - Avoid unequal settlement. - Prevent the lateral movement of the structure. - Increase structural stability. ## Types of Foundation ### A. Shallow Foundation - the width of the foundation is greater than the depth of the foundation. 1. **Isolated Spread Footing** - the most common and simplest type of footing and used to support a single column only. 2. **Wall or Strip Footing** - used to distribute loads of structural load-bearing walls to the ground and runs along the direction of the wall. Stone, brick, reinforced concrete etc. are used. - Width = 2-3 times the width of wall 3. **Combined Footing** - provided when the SBC is low and isolated footings are overlap to each other. They may be rectangular, tee-shaped or trapezoidal in shape. 4. **Strap or Cantilever Footing** - consists of single footing connected with a strap beam. Generally, when the edge of the footing cannot be extended beyond the property line the exterior footing is connected by strap beam with interior footing. 5. **Raft or Mat Footing** - consist of a concrete slab placed over the entire building area. Used when the SBC is relatively low. ### B. Deep Foundation - the width of the foundation is smaller than the depth of the foundation. ## MODULE 3. Structural Plans # TARLAC STATE UNIVERSITY - College of Engineering & Technology ## Civil Engineering Department ### Engr. Orlando Cruz Sico Jr. ## CEP352/351C - Building System Design & Computation ## MODULE 4.1 # FOUNDATION DESIGN & DETAILING ## Foundation Plan - A plan layout of footings, footing tie beams, wall footing, columns and slabs on fill. All in reference to grid lines. ### Footings - are strutural members used to support columns and walls. And to distribute column & wall loads. ## Wall Footing - A strip footingused to support all types of wall (load bearing, non-load bearing, retaining, etc.) - Specifications: CHB Wall (6” CHB for all exterior walls, & 4" CHB for all interior walls). ## Isolated Footing - Isolated footing is the single or individual footing which transfers load to the underground soil. It is provided when a single column is to be provided. A foundation is the part of the substructure which makes a direct contact or rested inside the ground. ### Notes: 1. No footing shall rest on fill 2. Minimum concrete cover = 75mm 3. Section 5.15.7, the depth of footing above bottom reinforcement may not be less than 150 mm for footing in soil. - The required footing area A as per NSCP Section 5.15.2.2 is: ### For permissible soil pressure, we should take into account the weight of all objects above the lower base of the footing, we will call this effective soil pressure, *qe*. ### Then; L = W = √Areq'a if square footing. ### For the depth of footing: ### Ultimate pressure is to be considered to for finding the depth of the footing, ### For isolated footing, the critical sections for shear are discussed as follows: ### The shear strength of slabs and footings in the vicinity of the columns, concentrated load, or reactions is governed by the more severe of the two conditions. ### For the thickness of the footing: ## Distribution of flexural or Main Reinforcement - Footing may be classified as a one-way footing or two way footing. One-way footings are those, which are reinforced in one direction only, while two-way footings are reinforced in two directions. - For simplification and for plates purposes only we will be using minimum requirement for flexural reinforcement of the footing ## Sample Problem: Prepare a footing detail for grid B-2. SBC = 120kPa, f'c=20.7 Mpa ## MODULE 4.1 Foundation Design and Detailing